Conception

The onset of pregnancy, marked by implantation of the blastocyst; the formation of a viable zygote.

Fertilization of an ovum by a sperm cell.

In relation to pregnancy, the act of fertilization, in which the sperm enters the egg (ovum) and forms a zygote. Attempts to avert conception are often called contraception, family planning, or birth control. In cases of infertility, a variety of methods are used to achieve conception.

The fertilization of an egg by a sperm that initiates pregnancy. During sexual intercourse, 300 million or so sperm are ejaculated into the vagina. About 3 million of them penetrate the cervix to get to the uterus; the rest are killed by vaginal secretions or are excreted from the body. The sperm that reach the egg secrete an enzyme that breaks down the outer covering of the egg. Once a single sperm has penetrated the egg, the outer covering immediately changes, to prevent other sperm from entering. The nucleus in the head of the sperm and the nucleus of the egg fuse to form a fertilized egg, also called a zygote. The zygote is made up of a unique combination of genes, half of which come from the man’s sperm and half from the woman’s egg.

The start of pregnancy, when a male germ cell (sperm) fertilizes a female germ cell (ovum) in the fallopian tube.

Conception signifies the complex set of changes which occur in the ovum and in the body of the mother at the beginning of pregnancy. The precise moment of conception is that at which the male element, or spermatozoon, and the female element, or ovum, fuse together. Only one-third of these conceptions survive to birth, whilst 15 per cent are cut short by spontaneous abortion or stillbirth. The remainder — over one-half — are lost very early during pregnancy without trace.

The process of conception involves the union of a woman’s ovum (egg) with a man’s sperm, which is subsequently followed by the implantation of the resulting blastocyst into the uterine lining. This significant event signifies the initiation of pregnancy.